This might be totally obvious, but I have never used anything Eurorack, so I thought I should doublecheck: can I use CV from Moogerfoogers to manipulate things on the Subharmonicon? For example, use the LFO from the MF-103 to sweep the filter frequency on the Subharmonicon?
Is it simply a matter of using a cable with 1/4" on one end and whatever Eurorack is on the other end?
Yes, they will work together just fine with a 1/8" to 1/4" cable. Just be aware that some MF inputs expect a TRS expression pedal / plug, not a TS plug.